This invention relates to vehicle components incorporating polymeric elements with members, casings or gaskets formed thereon and, more particularly, to vehicle component assemblies including vehicle exterior lighting assemblies such as a composite headlamp assembly incorporating a hard coated polycarbonate lens element bonded to a molded polymeric gasket.
In recent years, vehicle headlamp assembly designs have been driven by body styling demands. The lenses of the newer headlamp assemblies are more contoured so that they follow the contours of the vehicle body. Traditional headlamp assemblies typically included a stainless steel bezel which permitted the lens to be mounted in an opening in the vehicle body. More recently, headlamp assemblies include a preformed gasket which is subsequently attached, for example by an adhesive to the peripheral portion of the lens, which permits the lens to be fitted more closely with the body of the vehicle. Such preformed gaskets are, however, difficult to tool and, in some cases, their installation is difficult and labor intensive. Moreover, conventional lenses are now typically molded from a polycarbonate resin. Since polycarbonate lenses are vulnerable to abrasion from road debris and the elements and to discoloration from ultraviolet radiation, the lenses are coated with a hard coat to provide a durable outer surface which is resistant to scratching and which protects the polycarbonate lens from ultraviolet radiation. Heretofore, these hard coatings have inhibited adequate adhesion between the preformed gasket material and the lens. Consequently, in order to improve the adhesion of the gasket to the lens, some conventional gaskets and lenses include structures to provide mechanical interlocking of the gasket to the lens to supplement the bond provided by the adhesive.
Referring to FIGS. 14A and 14B, one conventional, prior known polycarbonate lens (100) includes a first slotted groove (102) along its peripheral edge (104) to provide an anchorage for a conventional preformed gasket (106), as will be more fully described below, a second slotted groove (108) along its peripheral edge for aligning and holding the gasket while it is installed on the lens, and a projecting flange (110), which also assists in the alignment and retention of the gasket (106) on the lens during the installation process. As a result, the molding apparatus for the lens requires complicated tooling, and the lenses are subject to tight tolerances.
The preformed gasket (106) includes corresponding structures that interlock with the lens grooves and flange. To install the gasket, an adhesive is applied to the gasket or lens perimeter, and a first end (112) of the gasket is seated in the first slotted groove (102) to anchor one end of the gasket (106) while the gasket is stretched around the perimeter of the lens. As the gasket is stretched around the perimeter, an intermediate portion of the gasket is then seated in the second slotted groove (108) to align the gasket and provide further mechanical interlocking of the gasket to the lens. Then the second of end (114) of the gasket is wrapped around the perimeter of the lens and seated in the first slotted groove (102) adjacent the first end of the gasket such that the gasket ends define a break or space 115 (FIG. 14A). In this manner, these grooves and flange of the lens and corresponding structures on the gasket cooperate to align the gasket and to mechanically retain the gasket on the lens while the adhesive cures and provide mechanical interlocking of the gasket to the lens. Such process is often difficult and time consuming. Also, the retention of the gasket on the lens is sometimes less than adequate, as is the adhesion between the gasket and lens. While these gaskets have improved the fit-up of the headlamp assembly with the contoured vehicle body, the apparatus used to form these gaskets is also difficult and expensive to tool.
Further, gaskets (106) may be formed with retainers or tabs (116). The retainers (116) project from the gasket and secure to a housing by fasteners to provide a means for temporarily securing the lens and the gasket to the housing during installation. These retainers further complicate the molding process of the gasket. In some applications, the gasket is molded from two materials, with the second material forming the retainers having a greater durometer hardness to increase the stiffness of the gasket where the retainers project from the gasket. Again, this process increases the cost of the gasket and is also difficult to tool.
Despite the improved fit up, these preformed gaskets may not provide the desired life expectancy and may require reinstallation or replacement. Furthermore, because of the geometry of the gasket, there may also be a gap between the first and second ends of the gasket such as that shown at 115 in FIG. 14A. This gap may affect the aerodynamics of the vehicle body or the wind noise of the assembly. Moreover, installation of these preformed gaskets is labor intensive, requiring manual manipulation of the gasket around the lens. This manual manipulation may lead to worker fatigue and, ultimately, may increase the number of defective installations and the cost of the vehicle.
Consequently, there is a need for vehicle component assemblies which incorporate resinous elements, especially hard coated polycarbonate lenses of vehicle headlamp assemblies, and cooperating gaskets of molded members which will exhibit improved adhesion between the gasket or molded member and the resinous element. Moreover, there is a need for such assemblies which can be manufactured and installed with significantly reduced labor, time, and costs.